1. Field of the Invention
The present invention relates to an information processing apparatus, such as a host computer, which transmits encoded image data to a printer, and to a printer which prints images based on encoded image data received from the apparatus.
2. Description of the Related Art
Printing systems in which encoded image data is transmitted between a host computer and a printer are well known in the art. Such systems are typically called "host-based" printing systems, meaning that image data is encoded in the host computer, and transmitted to the printer for printing.
In operation, host-based printing systems transmit encoded image data from a host computer to a reception buffer in a printer. Thereafter, circuitry in the printer converts the encoded image data stored in the reception buffer into video signals, which are then provided to a printer engine. The printer engine then prints images based on these video signals.
In systems of the foregoing type, the reception buffer typically has a limited storage capacity. Consequently, the reception buffer may not be able to store an entire page of encoded image data that is transmitted from the host computer. Due to this limited storage capacity of the reception buffer, printing errors result when a conventional system tries to print a page which is too large for its printer's reception buffer. The most common of these errors is known as "print overrun". In print overrun situations, images are not printed on the proper areas of a sheet of recording paper. As a result, large blank spaces will appear on recording sheets in places where images should be printed.
Conventional systems suffer from at least one other drawback resulting in errors similar to those described above. Specifically, in conventional host-based printing systems, it is necessary to transmit encoded image data from the host computer to the printer at the same timing at which paper is ejected (i.e., fed, conveyed and expelled) from the printer. Problems arise with these systems, however, if the timing at which encoded image data is transmitted from the host computer becomes desynchronized from the timing at which paper is ejected from the printer. In these cases, printer errors, such as print overrun, can occur regardless of whether or not a "huge page" (i.e., a page too large for the reception buffer) of encoded image data is being transmitted to the printer.
In view of the foregoing, in conventional systems, a processor in the host computer must devote at least a part of its energies to ensuring that synchronism is maintained between transmitted encoded image data and paper ejection. Consequently, the host computer may be unable to perform other, possibly higher priority tasks, without risking printing errors.
Thus, there exists a need for a printing system which reduces the burden on a host processor to maintain the foregoing synchronization, and which is able to print images based on "huge pages" of encoded image data without requiring additional memory and with relatively few print errors.